Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [backup]

For questions about backup circuits, such as a battery backup.

For questions about backup circuits, such as a battery backup.

70 questions
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1 answer

Coin cell battery recharging circuit for RTC backup power

I am designing a system that contains an RTC to for displaying the date and time on a user interface, as well as log events with time stamps. In this particular case, the system gets powered-on at intervals ranging from once a day to once every two…
wave.jaco
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2 answers

Battery Charging Backup Circuit

I am relatively new to electronics and circuits. I'm modifying an alarm clock to have a battery backup. I've found a few circuits that show how to build a battery backup circuit and it makes a lot of sense to me. A few of these circuits allow the…
namarino41
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1 answer

Can a memory backup supercap hold on for more than 2 weeks?

Most RTC chips have a VBATT input for backup power supply; besides a battery, you can use a supercap there, e.g. using the following scheme: simulate this circuit – Schematic created using CircuitLab How much time would the cap provide for your RTC…
anrieff
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3
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1 answer

Will this DC UPS with off the shelf components for home network and laptop work?

I am trying to build a DC UPS to power modem, router which have power requirements of 12V 2A and a laptop which has power requirement of a 20V 3.5A. I am planning to use a AC to DC SMPS which is capable of 24V 20A which is connected to a solar…
rej
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3
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1 answer

Integrated 5V uninterruptible power supply (UPS) with a lithium cell?

I'm trying to figure out the best way to implement a UPS for an embedded system that runs from a 5V supply. Essentially the system has a 48v to 5v, 1.2A output DCDC converter that powers my system. The 5v output supplies a bank of relays, as well as…
Sensors
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5 V holdup/ temporary backup circuit

I have a project where I'm using an android tablet to power a serial relay, the relay is 20 m from the tablet so I'm using a USB C > USB A hub and a self powered USB over CAT6 extender. When the tablet is charging through the input in the USB hub…
Tim
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Can I connect a separate charger and inverter to use a LiFePO4 battery as a backup for a household pump?

I have the following equipment and want to know what I need to make this a functional battery backup for a sump pump. 12 V, 100 Ah Smart LiFePO4 battery Victron BlueSmart IP65 Charger 12 VDC, 15 A I understand the missing parts are an inverter, a…
cr0
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2
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1 answer

Frequency reading 180 Hz on only one line to line measurement in three-phase backup 60 Hz LP gas powered generator in idle mode

I am running into an issue I don't understand why is happening. I have found how to "fix" it, but I am interested in ideas on what the actual source of the issue is Short version: I have a LP gas powered three phase 38 kW Generac generator that…
Andrés Marquina de Hoyos
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SAM4N Backup Mode - no wakeup

I do have an ATSAM4N and try to go to backup mode as soon as the external power is turned off to keep the RTC time running. Therefore, a battery is added to support VDDIO. I manage to get the SAM4N in backup mode by activating the supply monitor…
Traummaennlein
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1 answer

5V battery backup supply for GPS

I designed a circuit to do the switching from a 12V car battery to a 8.4V Li-Po battery with a relay. Both batteries go through an LM7805 regulator to supply a constant 5V to a Raspberry Pi. When I connect the output of the circuit to the Raspberry…
Felipe_Cortes_Z
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1 answer

Replacing Dallas NVRAM with larger capacity variant?

This DS1225AB-200 (8k x 8 = 64kB NVSRAM) is from 1995 and is probably dead (cannot measure from the outside.) The only close replacement in stock is a DS1230AB-100 (32k x 8 = 256kB.) Looking at the two datasheets, the pin-outs are identical…
rdtsc
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2
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Using two diodes as a simple power supply backup switch

I saw this module as a "battery emergency switch module" for $2 on aliexpress: which is just a relay energized by the external power supply, and when the external supply is gone, connects the battery to output. despite a relay could switch higher…
Tirdad Sadri Nejad
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2
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Apc backup time calculation

I have APC BX1100C UPS for my pc. it has 2x7.2Ah battery. I have connected to it a router 12v 0.5a, and a monitor 19v 1.3a. Expected it to run 10 hours but it switched off after 2 hours. Does it mean the batteries capacity has reduced from usage ?…
Ron
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Power supply charging backup power - current flow via mosfet

I have following diagram on falstad Top +5V is main PSU (12V 10A). Bottom +5V is battery (12V 2.3Ah). I have load about 2-3A so I dont think diode is good solution. Well I am trying to achieve following: While PSU is plugged then run circuit from…
user1085907
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2
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2 answers

Switch to battery when voltage supply drops certain threshold

I have made this circuit but can't quit make it work. Vext is my main supply from a car (9 - 14V) Vbat is 8 AA batteries (10 - 13V) Vout supplies power to a SMPS As it is now, supply "fades" between Vext and Vbat when Vext is around the…
Brian_DK
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